Anticorrosion additives for synthetic lubricants



los -1e W MTRQQ X R Patented Jan." 27, r t

l i awn-J ' PATENT OFFICE ANTICORROSION ADDITIVES FOR SYNTHETIC LUBRICANTS William A. Zisman, Washington, D. 0., and Hayward R. Baker, Mt. Rainier, Md., asslgnors to the United States of America, as represented by A the Secretary of the Navy N Drawing. Application April 15, 1944,

Serial No. 531,240

'tClaims. (01. 352-32) (Granted under the act of March 3, .1883, as

hydrocarbons, and of lower viscosity at low temperatures, a new type of oil, or series of oils, has been developed wherein mixed alkylene oxides play an important part in the molecular structure. These oils,.briefly, are copolymers of varioilsof less inflammability than the petroleumarnended April 30, 1928; 370 0. G. 757) Typical, preferred compounds within these groups are described more in detail as follows:

- ous alkylene oxides, such as ethylene oxide and propylene oxide, and they are known in the trade as B-O-lOO oils.

In spite of their unusual physical properties,

these oils, by themselves, are rather limited in application because they are relatively corrosive when compared to the best protected hydrocarbon oils.

This invention provides a group of organic compounds which are soluble and compatible with the B-Q-IOO oils at high and low temperatures and which inhibit the corrosive action of the oils when dissolved therein in small quantities. The invention also includes these oils containing the antieorrosion additives referred to, as new compositions of matter.

Not all organic compounds which are soluble in these oils are capable of inhibiting their corrosive action. The group of the compounds which are effective may be classified generally in the form of several sub-groups, namely:

Naphthenic acids having molecular weights be- "tween about 180 and 440, metal naphthenatesof said acids, n-alkoxy derivatives of benzoic acid wherein the alkyl chain has from 6 to 18 carbon atoms, esters of anhydro-sorbitol and anhydromannitol with aliphatic monocarboxylic acids having from 6 to 18 carbon atoms, saturated and unsaturated aliphatic amines having from 6 to 18 5 carbon atoms, metal soaps of aliphatic acids from caproic to stearic, aliphatic alpha-hy-droxy acids l from alpha-hydroxy caproic to alpha-hydroxy stearic, saturated aliphatic acids from caproie to palrnitic, monocarboxylic aliphatic acids containing a triple bond and having from 6 to 18 carbon atoms, alkaryl derivatives of aliphatic acids from caproic to stearic the alkaryl group consisting of an alkyl chain from 1 to 18 carbon atoms and an aryl group, and acid-amide complexes formed by reacting unsubstituted and aryl-substituted aliphatic acids from caproic to stearic with aromaticamines and with aliphatic amines having from 1 8 to 18 carbon atoms.

The aliphatic series of acids from lauric to palmitic protects steel from corrosion when in a mixture of B-O-100 oil and water. Also the acids from caproic to lauri'c are useful, although larger quantities will be required to give complete protection. The shorter chain acids are useful at very low temperatures such as minus 40 F. for lauric acid and even lower for those with 6 or 8 carbon atoms. Naphthenic acids with molecular weights of 180 to 440 are highly efiective attemperatures as low as minus 40 F., and other naphthenic acids of lower molecular weights are useful at still lower temperatures, although greater quantities are necessary. N The aliphatic amines from decyl amine to octadecyl amine are effective for temperatures" ranging from minus 40 F. upward, depending"- upon the chain length of the amine. The quantity used to secure protection, in general, is less within increasing chain lengths.

Other amines which are useful are those from decenyl and decendienyl to octadecenyl and octadecendienyl amine and mixtures of these. (In the table given below, a mixture of n-mono-octodecenyl amine and n-mono-octadecendienyl amine is illustrated.) These amines serve effectively as anti-corrosion agents in the B-O- oils of extreme temperature ranges including temperatures much lower than minus 40 F.

Ethylphenyl stearic acids and the related compounds from methyl to octadecyl and phenyl, benzyl, tolyl, xylyl and naphthyl substituted aliphatic acids from caproic to stearic are excellent additives and are useful from temperatures at the upper limits of normal use to below minus 40 F. Preferably acombination of shorter chain acids is used in the oils which are to be subjected to extremely low temperatures. Some of the additives covered within this sub-group and which are particularly useful are as follows: phenyl stearic acid, xylyl stearic acid, tolyl stearic acid, xenyl stearic acid, cumyl stearic acid, pseudo cumyl stearic acid, diethylphenyl stearic acid, diisopropyl phenyl acid, tetrahydronaphthyl stearic acid, chlorophenyl stearic acid.

The various metal aphtnatgs are useful, differentones having a mu aerit over different rates are satisfactory corrosion preventatives,

assars some for temperatures in the higher range and others over a wider range of temperatures. Zinc stearate is efiective both in the higher ranges and as low as minus 20 F.

Alpha hydroxy substituted acids from caproic to stearic are satisfactory addition agents, of which alpha hydroxy palmitic acid is eiifective at temperatures even below minus 40 F.

Para-n-dodecyloxy benzoic acid and the related The corrosion rating was determined by a modification of the A. S. T. M. turbine corrosion test D-665-42-T. The modification consisted of using a flat bottom pyrex cylindrical container 80 by 18 mtg. in sim. The specimen was a piece of cold rolled steel 4.25 by 0.25 by 0.03 inch in size. The. specimen was attached directly to the shaft of a motor and serves as it own stirrer, revolving at approximately 1080 R. P. M. The lower 1.78

ortho, meta and para acidsfrom hexyl to octa- 1 inches of the specimen is the only part considered decyloxybenzoic acids serve at both high and low in the test as it alone is in contact with the liquid temperatures. Stearolic acid, 9-octadecynoic sample. The sample consists of 9 parts by volacid (an 18 carbon atom acid with an unsaturated ume of 13-0-100 oil, lpart of distilled water contriple bond) and similar unsaturated aliphatic taining the additive compound, thus giving a mixacids from hexanoic to stearic acid are useful at ture of 90% B-O-100 oil and about 10% water. high temperatures and down to temperatures The steel specimen was rotated in the mixture below minus 40 F. for 48 hours at 140 F.

S rbitan mono-oleate, which is an ester of an Many variations will be apparent to those anhydro poiyfiyd'f'i'c alcohol, and esters resulting skilled in the art, and the invention should not from the esterification of one or more hydroxyl go be limited other than as defined by the appended groups of an anhydro-sorbitol or an anhydroclaims. mannitol with one or more of the aliphatic mono- Th inven ion described herein y be menucarboxylic acids are effective additives over the factured and used by or for the Government of average temperature range and to temperatures the United States of America for governmental below minus 40 F. V my purposes without the payment of any royalties A series of compounds or mixtures of comthereon or'therefor. pounds or complexes made by-combining equiv- We claim: alent weights of aliphatic acids from caproic to 1. A synthetic hydraulic and lubricating fluid stearic, or phenyl, benzyl, tolyl, or naphthyi subcomposition which comprises essentially a polystituted aliphatic acids with an equivalent weight 8" alkylene oxide fluid having dissolved therein a of amine from octyl to octadecyl or aromatic corrosion inhibitor, which inhibitor comprises at amines or aromatic substituted aliphatic amines, least one compound selected from the group conare highly eifective anti-corrosion additives. sisting of aliphatic acids, alkaryl derivatives of These complexes are most easily prepared by aliphatic acids, and metal soaps of said acids, dissolving the acid and amine in alcohol warm- 3:, wherein the aliphatic acid is one having from ing slightly and mixing well. Then the alcohol about 6 to 18 carbon. atoms in the aliphatic chain. is allowed to evaporate, leaving the acid amine 2. A synthetic hydraulic and lubricating fluid complex which is used as the additive for the composition which comprises essentially a poly- ZB-O-lOO oils. All of these series of complexes alkylene oxide fluid and about 0.1 to about 2 per are useful over very wide temperature ranges 40 cent by weight of an inhibitor dissolved therein, and some of them are desirable additives for use which inhibitor comprises at least one compound at temperatures below minus 40 F. is selected from the group consisting of aliphatic Mixtures of any of these additives may be used acids, alkaryl derivatives of aliphatic acids, and in the B-O-100 oils to achieve characteristics metal soaps of said acids, wherein the aliphatic dependent on more than one type of additive. 45 acid is one having from about 6.to about 18 carbon A comparison of the effects or different specific atoms in the aliphatic chain. additives on the B-O-100 oils is shown in the 3. A synthetic fluid lubricating composition following table, the meaning of the abbreviawhich comprises essentially a polyalkylene oxide tions being given below: fluid and about 0.1 to about 2 per cent by weight M Table v P s 1 mu Additive ,Lubricant used 35%? Ad i ti by fi urin ttfii-ZL f3 Weight used two weeks 0." F. lauric acid 0 0. 6 B 25 S 40 myristlc acid. 0 0.5 S 25 B palmitic acid 0 o. e s 100 s o naphthenic acid M. W.240 0 1.0 S 8 naphthenic acid M. W.440 0 i 0. 5 B 25 S 40 hexadecyl amine 250-B-0-l00 0 1.0 S 25 B 0 mixture of n-mono octadecenyl and n-mono octadecendienyl amine. 400-3-0-100 0 1.0 B 25 S 40 and 250-BOl00 ethyl henyl stearic acid 250-B0-l00 0 0. B 25 B 40 pheny stearic acid 250-8-0-100 0 0. 5 S 25 8 40 xylyl stesric acid.- 250-B0l00 0 0. 6 S 25 S 40 zinc naphthenate 250-13-0-100 0 0.5 S S 40 zinc stearate 250-B-0-l00 0 0. 2 S 100 S 20 palmitic 2-hydroxy acid .i 0 0. 5 S 25 S 40 p. n. dodec loxy benzcic acid.. 0 0. 2 S 25 S 40 stearolic ac d 4. 0 1.0 S 25 S 40 sorbitan monooleute 0- 0 1.0 S 25 S 40 stearic acid and phenyl alpha naphthyl amine complex 0 0. 75 S 100 8 0 stearic acid and dodecyl amine complex. 0 1.0 8 100 S 20 stearic acid and tetraclecyl amine complex. 250-13-0-100 0 0. 76 8 loo 8 0 stcaric acid and hexadecyl amine complex 250-B-0-100 0 0. 75 S 100 8 0 stearic acid and octadecyl amine complex 250-3-0-100 0 0. 75 B 100 S 0 S=soluble. The number preceding the 13-0-100" in column 2 indicates the relative degree of polymerization of the oil. In some cases the additive is soluble in the lubricant used only on long standing. If, however, it is warmed slightly it is soluble immediately.

it a

which comprises essentially a polyalkylene oxide.

fluid and about 0.1 to about 2 per cent by weight of an inhibitor dissolved therein which comprises at least one alpha-hydroxy acid from alpha hydroxy caproic to alpha hydroxy stearic.

6. A synthetic fluid lubricating composition which comprises essentially a polyalkylene oxide fluid and about 0.1 to about 2 per cent by weight of an inhibitor dissolved therein which comprises at least one saturated aliphatic acid from ,caproic to palmitic.

6 '7. A synthetic hydraulic and lubricating fluid composition'which comprises essentially a polyalkylene oxide fluid and about 0.1 to about 2 per cent by weight of lauric acid dissolved therein.

WILLIAM A. ZISMAN. HAYWARD R. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED s'rATEs PATENTS Number Name 4 Date 2,308,502 Farrington Jan. 19, 1943 2,296,342 Gaylor et a1. Sept. 22, 1942 2,293,868 Toussaint Aug. 25, 1942 2,281,676 Cook May 5, 1942 2,268,608 McNulty et a1 Jan. 6, 1942 2,152,683 Eichwald Apr. 4, 1939 2,149,498 Bludworth Mali-7. 1939 

